org.springframework.util

类 MethodInvoker

java.lang.Object

org.springframework.util.MethodInvoker

public class MethodInvoker
extends Object

Helper class that allows for specifying a method to invoke in a declarative fashion, be it static or non-static.

Usage: Specify "targetClass"/"targetMethod" or "targetObject"/"targetMethod", optionally specify arguments, prepare the invoker. Afterwards, you may invoke the method any number of times, obtaining the invocation result.

从以下版本开始:

19.02.2004

作者:

Colin Sampaleanu, Juergen Hoeller

另请参阅:

prepare(), invoke()

字段概要

字段

限定符和类型	字段和说明
protected Class<?>	targetClass

构造器概要

构造器

构造器和说明
MethodInvoker()

方法概要

限定符和类型	方法和说明
protected Method	findMatchingMethod() Find a matching method with the specified name for the specified arguments.
Object[]	getArguments() Return the arguments for the method invocation.
Method	getPreparedMethod() Return the prepared Method object that will be invoked.
Class<?>	getTargetClass() Return the target class on which to call the target method.
String	getTargetMethod() Return the name of the method to be invoked.
Object	getTargetObject() Return the target object on which to call the target method.
static int	getTypeDifferenceWeight(Class<?>[] paramTypes, Object[] args) Algorithm that judges the match between the declared parameter types of a candidate method and a specific list of arguments that this method is supposed to be invoked with.
Object	invoke() Invoke the specified method.
boolean	isPrepared() Return whether this invoker has been prepared already, i.e. whether it allows access to getPreparedMethod() already.
void	prepare() Prepare the specified method.
protected Class<?>	resolveClassName(String className) Resolve the given class name into a Class.
void	setArguments(Object... arguments) Set arguments for the method invocation.
void	setStaticMethod(String staticMethod) Set a fully qualified static method name to invoke, e.g.
void	setTargetClass(Class<?> targetClass) Set the target class on which to call the target method.
void	setTargetMethod(String targetMethod) Set the name of the method to be invoked.
void	setTargetObject(Object targetObject) Set the target object on which to call the target method.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

字段详细资料

targetClass

@Nullable
protected Class<?> targetClass

构造器详细资料

MethodInvoker

public MethodInvoker()

方法详细资料

setTargetClass

public void setTargetClass(@Nullable
                           Class<?> targetClass)

Set the target class on which to call the target method. Only necessary when the target method is static; else, a target object needs to be specified anyway.

另请参阅:

setTargetObject(java.lang.Object), setTargetMethod(java.lang.String)

getTargetClass

@Nullable
public Class<?> getTargetClass()

Return the target class on which to call the target method.

setTargetObject

public void setTargetObject(@Nullable
                            Object targetObject)

Set the target object on which to call the target method. Only necessary when the target method is not static; else, a target class is sufficient.

另请参阅:

setTargetClass(java.lang.Class<?>), setTargetMethod(java.lang.String)

getTargetObject

@Nullable
public Object getTargetObject()

Return the target object on which to call the target method.

setTargetMethod

public void setTargetMethod(@Nullable
                            String targetMethod)

Set the name of the method to be invoked. Refers to either a static method or a non-static method, depending on a target object being set.

另请参阅:

setTargetClass(java.lang.Class<?>), setTargetObject(java.lang.Object)

getTargetMethod

@Nullable
public String getTargetMethod()

Return the name of the method to be invoked.

setStaticMethod

public void setStaticMethod(String staticMethod)

Set a fully qualified static method name to invoke, e.g. "example.MyExampleClass.myExampleMethod". Convenient alternative to specifying targetClass and targetMethod.

另请参阅:

setTargetClass(java.lang.Class<?>), setTargetMethod(java.lang.String)

setArguments

public void setArguments(Object... arguments)

Set arguments for the method invocation. If this property is not set, or the Object array is of length 0, a method with no arguments is assumed.

getArguments

public Object[] getArguments()

Return the arguments for the method invocation.

prepare

public void prepare()
             throws ClassNotFoundException,
                    NoSuchMethodException

Prepare the specified method. The method can be invoked any number of times afterwards.

抛出:

ClassNotFoundException

NoSuchMethodException

另请参阅:

getPreparedMethod(), invoke()

resolveClassName

protected Class<?> resolveClassName(String className)
                             throws ClassNotFoundException

Resolve the given class name into a Class.

The default implementations uses ClassUtils.forName, using the thread context class loader.

参数:

className - the class name to resolve

返回:

the resolved Class

抛出:

ClassNotFoundException - if the class name was invalid

findMatchingMethod

@Nullable
protected Method findMatchingMethod()

Find a matching method with the specified name for the specified arguments.

返回:

a matching method, or null if none

另请参阅:

getTargetClass(), getTargetMethod(), getArguments()

getPreparedMethod

public Method getPreparedMethod()
                         throws IllegalStateException

Return the prepared Method object that will be invoked.

Can for example be used to determine the return type.

返回:

the prepared Method object (never null)

抛出:

IllegalStateException - if the invoker hasn't been prepared yet

另请参阅:

prepare(), invoke()

isPrepared

public boolean isPrepared()

Return whether this invoker has been prepared already, i.e. whether it allows access to getPreparedMethod() already.

invoke

@Nullable
public Object invoke()
                         throws InvocationTargetException,
                                IllegalAccessException

Invoke the specified method.

The invoker needs to have been prepared before.

返回:

the object (possibly null) returned by the method invocation, or null if the method has a void return type

抛出:

InvocationTargetException - if the target method threw an exception

IllegalAccessException - if the target method couldn't be accessed

另请参阅:

prepare()

getTypeDifferenceWeight

public static int getTypeDifferenceWeight(Class<?>[] paramTypes,
                                          Object[] args)

Algorithm that judges the match between the declared parameter types of a candidate method and a specific list of arguments that this method is supposed to be invoked with.

Determines a weight that represents the class hierarchy difference between types and arguments. A direct match, i.e. type Integer -> arg of class Integer, does not increase the result - all direct matches means weight 0. A match between type Object and arg of class Integer would increase the weight by 2, due to the superclass 2 steps up in the hierarchy (i.e. Object) being the last one that still matches the required type Object. Type Number and class Integer would increase the weight by 1 accordingly, due to the superclass 1 step up the hierarchy (i.e. Number) still matching the required type Number. Therefore, with an arg of type Integer, a constructor (Integer) would be preferred to a constructor (Number) which would in turn be preferred to a constructor (Object). All argument weights get accumulated.

Note: This is the algorithm used by MethodInvoker itself and also the algorithm used for constructor and factory method selection in Spring's bean container (in case of lenient constructor resolution which is the default for regular bean definitions).

参数:

paramTypes - the parameter types to match

args - the arguments to match

返回:

the accumulated weight for all arguments